QuickBooks: COMException (0x80040408): Could not start QuickBooks.

You may receive the following error when Sync & Save attempts to connect to QuickBooks:

System.Runtime.InteropServices.COMException (0x80040408): Could not start QuickBooks.

When Sync & Save attempts to connect to QuickBooks, if QuickBooks is not already running, then Sync & Save has to start up the QuickBooks process. If QuickBooks fails to start up successfully, then Sync & Save can not connect.

Please try the following steps to resolve this issue:

Make sure the Windows User Account Control (UAC) is set to the default security level. This setting is found under User Accounts in the Windows Control Panel.